High-resolution live cell imaging reveals the biogenesis of the apicoplast organelle in malaria parasites

The apicoplast organelle is a unique organelle of the Apicomplexa phylum of important eukaryotic parasitic pathogens causing diseases such as malaria and toxoplasmosis. This endosymbiotic organelle of prokaryotic origin is essential at every known stage of parasite`s complicated life cycles, and therefore identified as an important parasite-specific drug target. Despite its central cellular functions and clinical significance, little is known about the molecular mechanisms governing apicoplast development and biogenesis.

We propose to investigate the link between apicoplast dynamics and cellular division (schizogony). At first, we will focus on nuclear replication and division stages to assess whether apicoplast development is independent process by monitoring organelle elongation and branching in presence of nuclear DNA synthesis inhibition. For this purpose, we generated a genetically modified P. Falciparum strain in which green fluorescent protein specifically localized to the apicoplast by fusion to a specific translocation protein. A modified protocol was established to allow long-term live 3D imaging using a confocal microscopy approach, to characterize the morphology and kinetics of apicoplast`s life-cycle throughout the life cycle of the parasite.

We identified detailed sub-stages of apicoplast`s biogenesis of P. Falciparum, some of them have not been identified previously. We will further test whether these morphological changes are regulated by organelle-specific mechanisms using a pharmaceutical approach.

To further investigate the mechanisms that enable nuclear and apicoplast parallel division and sorting into individual daughter cells during cytokinesis, we will genetically-tag several parasite subcellular compartments along with m-Neon labeled apicoplast, including the nucleus, mitochondria and basal complex.